Field of the Disclosure
This disclosure relates to communications technology and more particularly to providing device-to-device or proximity communications services to devices used in wide-area networks.
Description of the Related Art
In general, proximity services (e.g., LTE-Direct) provide direct communications between devices using licensed or unlicensed frequency bands within a predetermined radius (e.g., a radius of 500 meters) to improve spectrum utilization, increase overall throughput, and reduce power consumption of radio access services. Device-to-device proximity services refers to communication services with little or no base station intervention between user equipment devices in proximity to each other. Functions for supporting proximity services include device-to-device proximity service discovery and device-to-device communication. Device-to-device proximity service discovery enables user equipment devices to use the wide-band area air interface to identify other user equipment devices that are in proximity. Device-to-device communication is the communication between at least two user equipment devices in proximity using the wide-band radio air interface to establish a direct link between user equipment devices without routing via a base station (e.g., eNode-B) or core network.
A typical user equipment device may be a host (e.g., send a discovery beacon) or a guest (e.g., sense the discovery beacon) for device-to-device proximity services. If a transmitter or sensor of the user equipment device is enabled at all times to facilitate discovery, discovery functions would drain the battery of the user equipment device. Discovery may be synchronous (e.g., searching during predetermined timeslots), but difficult to implement, or asynchronous (e.g., continuous searching) and having ease of implementation, but consuming higher-power. Accordingly, improved techniques for discovery are desired.